This invention relates to an automatic tape loading, cassette type, reproducing apparatus with intermittent tape shifting capability, and more particularly to a device for intermittently shifting the tape in minute quantities, with the apparatus in a still picture reproducing mode of operation.
In general, an apparatus for reproducing video signals produces a still picture by stopping the tape travel. During this operation, the rotating reproducing heads repeatedly scan and reproduce a selected track on the tape, and the still picture is thus reproduced.
In general, however, unrecorded bands, called "guard bands" are left between adjacent tracks on the tape for, the preventing effects such as beat disturbance between adjacent tracks.
At the time when the still picture is reproduced, the rotating heads scan the greater part of a guard band, depending on the stopping position of the tape. A normal picture image cannot be reproduced and, moreover, much noise will occur to produce an unsightly picture, since signals are not recorded on this guard band.
Accordingly, in order to produce a normal still picture, it is necessary to stop the tape at a position where the rotating heads will correctly scan the recorded track. However, when the tape is stopped in order to reproduce a still picture, the traveling is stopped irrespective of the relative positional relationships of the tape, rotating head, and the tracks. For this reason, it is quite possible for the tape to stop traveling at a position where the rotating heads happen to scan a guard band. In such a case, it is necessary to shift the tape stopping position so that the rotating heads will scan the track in a normal manner.
A video signal reproducing apparatus of the "open-reel" type may not provide automatic tape loading means. The tape is not contained in a cassette. The operator moves the tape slightly by manually rotating a reel, while observing the reproduced picture. When a normal still picture has been obtained, that is, when the rotating heads correctly scan the track, the tape shifting is stopped. However, in a reproducing apparatus of an automatic tape loading type, the reels are accommodated within a cassette, and the reels cannot be rotated manually. Furthermore, since the tape travel path is generally much more complicated for a cassette system than for an open-reel type, the tape friction during travel is great. If the tape is subjected to undue tension in order to forcibly shift it, the tape may be damaged. For example, an elongation may be imparted thereto.
Accordingly, there is a need for a device which will shift the tape at will through a very small distance, in order to produce a correct still picture in an automatic tape loading reproducing apparatus.